defer property
      
      bool
      get
      defer
      
    
    
The defer property of the HTMLScriptElement interface is a boolean
value that controls how the script should be executed. For classic
scripts, if the defer property is set to true, the external script
will be executed after the document has been parsed, but before firing
Document.DOMContentLoaded_event event. For
module scripts,
the defer property has no effect.
It reflects the defer attribute of the script element.
Implementation
external bool get defer;
      
      set
      defer
      (bool value) 
      
    
    
    
Implementation
external set defer(bool value);